1. Field of the Invention
The present invention relates to blood collection sets for safe and convenient handling of needles. More particularly, the present invention relates to a blood collection set including a needle assembly having a needle cannula which is retractable within a safety shield for protection from a used needle tip.
2. Description of Related Art
Disposable medical devices having medical needles are used for administering medication or withdrawing fluid from the body of a patient. Such disposable medical devices typically include blood collecting needles, fluid handling needles, and assemblies thereof. Current medical practice requires that fluid containers and needle assemblies used in such devices be inexpensive and readily disposable. Consequently, existing blood collection devices typically employ some form of durable, reusable holder on which detachable and disposable medical needles and fluid collection tubes may be mounted. A blood collection device of this nature may be assembled prior to use and then disassembled after use. Thus, these blood collection devices allow repeated use of a relatively expensive holder upon replacement of relatively inexpensive medical needles and/or fluid collection tubes. In addition to reducing the cost of collecting blood specimens, these blood collection devices help minimize the production of hazardous waste material.
A blood collection device or intravenous (IV) infusion device typically includes a needle cannula having a proximal end, a pointed distal end, and a lumen extending therebetween. The proximal end of the needle cannula is securely mounted in a plastic hub defining a central passage that communicates with the lumen extending through the needle cannula. A thin flexible thermoplastic tube is connected to the hub and communicates with the lumen of the needle cannula. The end of the plastic tube remote from the needle cannula may include a fixture for connecting the needle cannula to a blood collection tube or other receptacle. The specific construction of the fixture will depend upon the characteristics of the receptacle to which the fixture is to be connected.
In order to reduce the risk of incurring an accidental needle-stick wound, protection of used needle cannulas becomes important. With concern about infection and transmission of diseases, methods and devices to enclose or cover the used needle cannula have become very important and in great demand in the medical field. For example, needle assemblies commonly employ a safety shield that can be moved into shielding engagement with a used needle cannula to minimize risk of an accidental needle stick.
For example, U.S. Pat. No. 5,120,320 to Fayngold discloses an intravenous infusion set or a blood collection assembly with an automatic safety feature incorporating a needle cannula and a safety shield, in which the needle cannula can be pulled rearwardly such that the shield can be extended over the puncture tip of the needle. The assembly further includes flexible wings which can be used as means for securing the needle assembly to the skin of a patient during a medical procedure. Positioning of the shield over the needle, however, requires the user to maintain the shield with one hand while withdrawing the needle into the shield with the other hand, thus resulting in a complex two-handed operation for the medical practitioner.
U.S. Pat. No. 5,951,525 to Thorne et al. discloses a manually operated safety needle apparatus that includes two pairs of opposed legs adapted to move a shield of the apparatus to a position covering the used needle cannula. Such an assembly requires a complex arrangement with extensive mechanics for activation of the shield over the needle cannula, which can result in increased costs for manufacture and assembly. Additionally, activation of the needle assembly to move the shield into the proper position over the pointed distal end of the needle cannula requires movement of both pairs of legs toward each other, which can be awkward for the user.
In view of the foregoing, a need exists for a blood collection set including a shieldable needle assembly that achieves secure and effective shielding of a used needle cannula, which is simple and inexpensive to manufacture and easy to operate, and which has an improved ergonomic feel to the user.